442 HEPBURN— BIOCHEMICAL STUDIES 



Nepenthes have found application in medicine. "The water ab- 

 stracted from their leaf pitchers is an article of commerce in the East 

 Indies. The leaves and root of N. Boschiana, Krthls. are especially em- 

 ployed, chiefly as an astringent. "(18) 



II 



A Study of the Protease of the Pitcher Liquor of Nepenthes 



BY 



Joseph Samuel Hepburn, A.M., M.S., Ph. D. 



Broadly speaking, two hypotheses exist concerning the mechanism 

 of the proteolytic digestion within the pitchers of Nepenthes. One 

 view is that digestion results from the action of a protease, secreted by 

 the pitchers. The other view is that digestion is due to bacterial action. 

 A third factor to be considered is the autolysis of the tissues of the 

 dead insects. 



In the present study, the volume of the liquor secreted by a single 

 pitcher was always so small, that liquor could not be obtained from the 

 same pitcher both before and after stimulation. Very rarely indeed did 

 two pitchers mature on the same plant at the same time, thereby permit- 

 ting a comparative study of the liquor from both stimulated and non- 

 stimulated pitchers of the same plant. Differences due to individual 

 plants could not be entirely eliminated, but the problem was attacked by 

 several methods for the study of proteolysis, and a number of experiments 

 were made according to each method; the results obtained by all the 

 methods lead to the same general conclusions. 



Material for this research has been obtained from the following species 

 and hybrids of Nepenthes, grown in the Nepenthes House of the Univer- 

 sity of Pennsylvania: — ampullar ia, atrosanguinea, Chelsonli, Claytonii, 

 Dominii, Dyerinana, gracilis, Hamiltoniana, Henryana, Hookeriana, Mas- 

 tersiana, mixta, Morganiana, paradisae, Rafflesiana pallida, rufescens, 

 splendida, Wittei. 



Pitchers were always selected prior to opening. They were closely 

 watched; and the mouth of each pitcher was closed with absorbent cotton 

 as soon as the lid opened; the entrance of insects was thereby prevented; 

 and possible contamination of the pitcher liquor by the tissue enzymes 

 of the digested prey was entirely excluded. 



